A border gateway protocol (BGP) is a dynamic routing protocol and may be used for exchanging routing information in an autonomous system (AS). The AS includes multiple routers. Two routers in a same AS exchange the routing information via an internal BGP (IBGP) to create a flow path, specifically, the flow path is created through change of a next hop in the routing information, where their connection relationship is called an IBGP connection.
In general, all the routers in the AS are interconnected, for example, if one AS includes n routers, n (n−1)/2 IBGP connections are needed. Thus, when n is larger, a lot of network resources and management organization resources need to be consumed to achieve the IBGP connection. In order to reduce resource consumption, a certain router in one AS is usually used as a reflection router, other part or all of the routers are used as clients, each client establishes the IBGP connection with the reflection router, the reflection router reflects the routing information between the clients, the clients establish no IBGP connection with each other, and interconnection of all the routers in the same AS is achieved by the reflection router. It should be noted that all routers mentioned below do not include the reflection router and are used as the clients.
In the above-mentioned case of interconnecting all the routers in the same AS through the reflection router, after routing information sent by one router to the reflection router is reflected, a next hop in the routing information is an identifier of the router, and the next hop in the routing information cannot be changed. Currently, in this case, an outbound policy is generally configured on the router to determine the next hop in the routing information. However, this method is used for determining the next hop at the router side, resulting in complicated operation of the router; the outbound policy needs to be configured on each router, resulting in large network maintenance workload.